Plastic substrates are used, for example, in the automotive sector as trim strips, radiator grilles, outside rear view mirrors, or emblems on the exterior of a motor vehicle. In motor vehicle interiors, entirely metallic components are being increasingly replaced by plastic components that have a coating that gives them a metallic appearance.
The known and typical coating methods include electroplating. But this involves a significant strain on the environment so that considerable efforts are being made to replace the electroplating process with other methods.
A somewhat newer approach lies in first coating the plastic substrates with a basecoat and then covering this with a metal layer that is deposited from the gas phase. A corresponding method is described in EP 1 736 566. In this case, a UV-hardening polymer layer is applied to a substrate, which is then coated by means of physical deposition from the gas phase, for example with a chromium or chromium-like layer that constitutes the outermost layer.
This method, however, has the disadvantage that the outermost layer is a PVD layer that is very thin and—since it is deposited onto a soft undercoat—is very susceptible to mechanical influences. This type of coating is not suitable for the use of such coated components on the exterior of a motor vehicle that is exposed to stone chipping and a wide variety of weather conditions.
In addition, automobile manufacturers not only require this type of component to have a metallic appearance, they also require a particular gloss level.
The object of the invention, therefore, is to disclose a method with which a component is given a metallic appearance with the required gloss level.